Cadillac Owners Forum banner

1 - 20 of 29 Posts

·
Registered
Cadillac
Joined
·
281 Posts
Discussion Starter #1
Hey guys, I had my rear diff replaced yesterday because it was starting to whine. The service tech told me they replaced the entire thing, whatever that means. Whelp, I Have no wine....but now..after the car sits for awhile I get a bad grinding noise comming from the rear when I start to back out and slowly start going foward. Once I drive awhile it's goes away. It seems like the car has to sit awhile and then it does it everytime.

anyone heard of this before? what could it be? It's going back to the dealership first thing monday, but I would love to point them in the right direction. I really wish there was a better caddi dealership out there close by. Seems everythign I get done there takes atleast 2 tries to fix, and they usually mess something else up.
 

·
Premium Member
2005 CTS-V
Joined
·
8,363 Posts
Hey guys, I had my rear diff replaced yesterday because it was starting to whine. The service tech told me they replaced the entire thing, whatever that means. Whelp, I Have no wine....but now..after the car sits for awhile I get a bad grinding noise comming from the rear when I start to back out and slowly start going foward. Once I drive awhile it's goes away. It seems like the car has to sit awhile and then it does it everytime.

anyone heard of this before? what could it be? It's going back to the dealership first thing monday, but I would love to point them in the right direction. I really wish there was a better caddi dealership out there close by. Seems everythign I get done there takes atleast 2 tries to fix, and they usually mess something else up.
The most common problem with newly installed (CTS-V) differentials has come from the omission of the friction modifier additive. This causes the clutch packs to stick together when they should slip. This causes "chatter" that is most noticeble in slow speed corners or if driving in lock-to-lock circle, but I suppose it could show up as the noise you describe. The other possibility that comes to mind is insufficent fluid.
 

·
Registered
Cadillac
Joined
·
281 Posts
Discussion Starter #4
So it that something that I should take it back to the dealership or will it work itself out over time?
 

·
Registered
05 CTS-V raven black
Joined
·
1,131 Posts
So it that something that I should take it back to the dealership or will it work itself out over time?
take it back and let them figure it out...
call in advance this should only take them about 20 minutes max to drain and fill the diff
 

·
Registered
'05 CTS-V, Powered by Chevrolet
Joined
·
835 Posts
Does it make the noise while making a turn? Then it could be the clutches and friction modifier should help. If you are going perfectly straight then the clutches are not the problem. You may then need to have someone look at what may have occurred during the removal & installation of the diff or the replacement diff itself.
 

·
Registered
Cadillac
Joined
·
281 Posts
Discussion Starter #7
hmmm, I would say it happens while I'm turning. When backing out turning and when going foward turning. But both of these while going at very very slow speeds.
 

·
Registered
Cadillac
Joined
·
281 Posts
Discussion Starter #9
Ok, I had to run to the store and noticed it does not do it at all when going straight. Only when making slow turns. I'll be at the dealership first thing in the morning. Do they have to drain all the diff fluid, or can they just add the stuff to the fluid thats already in there?

Also, should I refrain from driving it until I get it in there?
 

·
Registered
2005 Platinum CTS V-Headers+3in pipes
Joined
·
3,012 Posts
I got my diff replaced the other day too.. I asked the dealer if there was a breaking in procedure and he said no.. Is this true?

Those of you who have had your diff replaced what have you done to break it in?

Also Should i change the fluid to Amsoil severe Gear 75W-90??

don't mean to :hijack: it but its a similar topic..:hide:
 

·
Registered
'05 CTS-V, Powered by Chevrolet
Joined
·
835 Posts
Ok, I had to run to the store and noticed it does not do it at all when going straight. Only when making slow turns. I'll be at the dealership first thing in the morning. Do they have to drain all the diff fluid, or can they just add the stuff to the fluid thats already in there?

Also, should I refrain from driving it until I get it in there?
The clutches won't make noise going straight because they are not s
The dealer only needs to remove about 4oz of gear oil to make room for the 4oz bottle of friction modifier. (Unless the dealership didn't top-off the differential with the right amount of gear oil.)

I got my diff replaced the other day too.. I asked the dealer if there was a breaking in procedure and he said no.. Is this true?

Those of you who have had your diff replaced what have you done to break it in?

Also Should i change the fluid to Amsoil severe Gear 75W-90??

don't mean to :hijack: it but its a similar topic..:hide:
I would be easy on it for about the first 1,000 miles. This should reveal if the install was done properly and give the internal parts time to break in. After the 1,000 miles I would drain the original oil and fill it with the proper gear lube of your choice. If you are still under warranty, some will argue to only refill it with the grape scented GM synthetic gear oil meeting the GM specification. This makes complete sense since GM will look for any excuse to void a claim. I gambled and went with AMSOIL Severe Gear 75W-90. I figured GM cheaped out on enough stuff so I assume they might have with their gear oil. Amsoil has a pretty good reputation with convincing lab tests and a warranty.
 

·
Premium Member
2005 CTS-V
Joined
·
8,363 Posts
Ok, I had to run to the store and noticed it does not do it at all when going straight. Only when making slow turns. I'll be at the dealership first thing in the morning. Do they have to drain all the diff fluid, or can they just add the stuff to the fluid thats already in there?

Also, should I refrain from driving it until I get it in there?
Driving the car without the additive will not cause any permanent damage - just the chatter as the clutches do reluctantly what they should do freely.

As far as whether or not they will have to drain it first, it depends. I am told that the replacement units arrive with fluid in them. Some dealers just use them with that fluid, which is not the prudent thing to do (IMHO). In order to ensure the quality of the fluid the dealer should drain the unit and fill it with fresh fluid and additive. My dealer did this on mine.
 

·
Cadillac Technician
none
Joined
·
11,051 Posts
They have to drain enough to allow for the adding of the 4 oz of friction modifier they forgot to put in.
No big deal.
Might be a battle convincing them to do it.
Some guys have had a hard time explaining it to them.

Good luck.
 

·
Registered
Cadillac
Joined
·
281 Posts
Discussion Starter #14
Just what I need, another battle...lol. I go for my 2nd meeting w/ attorney this wed for a lawsuit against a former gym :/

I will try to explain it to them, but however they want to do it is fine w/ me. They will most likely want to put a brand new diff in there to try and stir up some business. You can hear the grinding no problem and anyone can listen and tell something is not right.
 

·
Premium Member
2005 CTS-V
Joined
·
8,363 Posts
I got my diff replaced the other day too.. I asked the dealer if there was a breaking in procedure and he said no.. Is this true?

Those of you who have had your diff replaced what have you done to break it in?

Also Should i change the fluid to Amsoil severe Gear 75W-90??

don't mean to :hijack: it but its a similar topic..:hide:
When I got my replacement differential the service manager gave me a very specific set of break-in instructions for the first 500 miles. Specifically, he told me to: (a) avoid constant speeds (not to be confused with engine rpm) as much as possible; (b) avoid driving more than 30 minutes at a time without a cool down (he wanted heat cylces, but no sustained heat accumulation); and (c) avoid WOT especially when the differential is cold.

Additionally, I changed the original fluid at 500 miles and with every oil change thereafter. I still use the GM stuff but believe Amsoil is an excellent alternative.

Since I only have 7k miles on the replacement differential I cannot claim to know if any of this will prevent the eventual whine.
 

·
Registered
2005 Platinum CTS V-Headers+3in pipes
Joined
·
3,012 Posts
Thanks guys,:thumbsup: i knew there had to be a procedure out there to break in the diff.. I am officially out of warranty now with only 22k on the clock.. Im plan on keeping this car till the wheels fall off, so I'm going to change all the fluids the next time i change the oil..
 

·
Registered
'05 LS6 V Stealth Grey; '14 Z71 SLT Sierra 1500 Stealth Grey
Joined
·
2,821 Posts
Change the rear with your lube of choice, but add the diff modifier first. I change mine every 10,000 miles. I have learned that I need the additive no matter which lube I use. Personal choice is Royal Purple.
 

·
Registered
Platinum 2004 CTS-V
Joined
·
4,914 Posts
Change the rear with your lube of choice, but add the diff modifier first. I change mine every 10,000 miles. I have learned that I need the additive no matter which lube I use. Personal choice is Royal Purple.
:yeah:
You always put the modifier in first so you don't have to worry about not having enough room for it after you add the diff fluid.

P.S. that dealership sounds like their service dept is full of morons
 

·
Registered
Cadillac
Joined
·
281 Posts
Discussion Starter #19
welp, looks like they are keeping my car yet another night. Took it in this morning, 2hrs later service guy calls me and says it's ready, but the mechanic wants to go for a ride we me. Now that alerted me thinking they didn't do anything to it, so when I got there I asked them what they did....he said added the friction stuff.

Then the mechanic comes out and wants to go for a ride. I tell em if he didn't do anything to it we wont have to go far. I start to back up and it starts grinding ... he says "wow" i didn't hear that because I never put it in reverse. No worries, it does it in foward too...I go around the first corner and it starts grinding, asked em if he heard that...he said yup that doesn't sound good...then says it was a factory default diff :thepan:


It drives me crazy, they call me to leave work and come pick up my car knowing they didn't do anything and they want to go for a ride with me so I can point it out to them. It was a very load grind and kinda shimmied the car, how can you miss it??

/sigh
 
1 - 20 of 29 Posts
Top